1. Field of the Invention
This invention relates generally to automatic machine tools programmable to perform multiple machining functions on a workpiece, and more particularly, to automatic machine tools having workpiece transfer apparatus operable to unload a workpiece from a storage bin and transfer the workpiece to a machining station.
2. Description of the Prior Art
Automated machine tools are well-known in the art, and perform a variety of cutting functions such as milling, drilling, threading, tapping, etc. on a workpiece. These machines are normally provided with a tool carousel that has numerous cutting tools mounted thereon for performing the variety of functions of the machine. The tool holder is generally a rotatable tool spindle mounted in a drill head adjustably mounted on a vertical column or quill for vertical movement. The tool spindle is mounted for rotation relative to the quill and is moveable axially with respect to the drill head. Additionally, the workpiece is secured to a worktable that is moveable in a x-y horizontal plane for providing a variety of positions to perform the various cutting operations.
The machine operation is performed by the rotatable tool spindle rotatably mounted on the drill head and arranged to be shifted vertically with respect to the workpiece. Precision cutting is performed, such that an aperture center may be precisely located with respect to the axis of the rotatable tool spindle and the combined movement of the worktable in its horizontal plane of movement. During the machining operation, the spindle is rotated at a pre-selected cutting speed and is feed downwardly by the drill head on the quill at a predetermined feed rate. The cutting tool is removably mounted in a chuck which is supported by the lower end of the rotatable spindle, and forms a part thereof. Additionally, a tool changer is adapted to remove the used tool from the chuck at the end of a cutting operation and replace the used tool with a pre-selected new tool in an automatic manner that eliminates lost time associated with manual tool changing operations.
All of these functions are carried out in a rapid efficient manner in order to bring about the most efficient operation of the machine tool. The automatic control of the machine tool is provided by a numerical control system operated under the control of a punched tape or other memory device which regulates the table so as to locate the cutting center with respect to the axis of the tool, the automatic selection of the rotatable spindle speed, the spindle feed rate on the quill, and other machine functions.
Automatic loading features, are usually not provided in automatic machine tools. It is often feasible to clamp the workpiece in a fixture outside of the machine area and slide it on rails into machining position after clamping. Present workpiece transfer systems require manual intervention to load the workpiece on a transfer shuttle system before the workpiece can be transferred to a workstation for machining. It would be desirable if an automatic machine had the capability to select a workpiece from a stack of material, transfer the workpiece to a machining station, and finally select a new workpiece from the stack of material. Such a machine tool having a much greater degree of automation provides more efficiency than machining operations with manual intervention.